..here the UI is telling me that I can move the uni which belongs to my teammate. Its green aura shows it belongs to my teammate yet the indicator is telling me I've yet to make a move with it.

I think this only occurs with mounts. There's probably some particular condition that triggers it, I can't recall what it is exactly. Perhaps it's when a creature that you previously cast is taken by your teammate, the UI gets confused when they get off it (remember - the act of them getting off it does not return it to you, it is still there's).